CN102802306B - Driving circuit and driving control method of light-emitting diode - Google Patents
Driving circuit and driving control method of light-emitting diode Download PDFInfo
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Abstract
The invention discloses a driving circuit and a driving control method of a light-emitting diode. The driving circuit of the light-emitting diode comprises a battery, an inductor, a double-electric-layer capacitor, a first field-effect tube, a second field-effect tube, a third field-effect tube, the light-emitting diode and a controller, wherein the inductor is connected with the battery; the double-electric-layer capacitor is connected between the negative electrode of the battery and the first end of the inductor; the first field-effect tube is respectively connected with the inductor and the double-electric-layer capacitor; the second field-effect tube is also respectively connected with the inductor and the double-electric-layer capacitor; the third field-effect tube is respectively connected with the inductor and the battery; the light-emitting diode is connected between the capacitor and the first field-effect tube; the controller is respectively connected with the first field-effect tube, the second field-effect tube and the third field-effect tube. According to the invention, the problem of lower energy utilization rate of the driving circuit of the light-emitting diode in the prior art is solved, so that the effects of improving the energy efficiency and element utilization rate and reducing the production cost of the system are achieved.
Description
Technical Field
The invention relates to the field of electronic circuits, in particular to a light emitting diode driving circuit and a driving control method thereof.
Background
When a camera, especially a flash lamp of a camera embedded in a mobile phone, works, a large current needs to be extracted from a lithium battery of the camera for the flash lamp to work, and the current often exceeds the maximum discharge capacity of the lithium battery, so that the application of the flash lamp is limited, and in order to solve the problem, a circuit scheme applying an Electric Double Layer Capacitor (EDLC) is provided in the prior art, and fig. 1a and 1b are respectively an external schematic diagram and an internal circuit structure diagram of a flash lamp driving circuit adopting one other scheme of the EDLC, as shown in fig. 1a, an AAT1282 circuit of an AATI company is adopted, the circuit is mainly realized by using a large-capacity high-voltage capacitor bank 1 as an energy storage unit of an LED flash lamp 2, wherein the large-capacity high-voltage capacitor bank 1 is formed by connecting two EDLCs in series, and the working principle of the circuit is as follows: the charging is performed at a higher intermediate voltage and then the current is regulated and output from the EDLC in a linear fashion, wherein an inductive boost is used to boost the lower cell voltage to the higher charging voltage. The prior art also provides a scheme for energy storage at the output end of the middle section by using ADP1560 from ADI corporation, the circuit diagram of which is shown in fig. 2, and the circuit is similar to the scheme of AATI except that the linear output regulating circuit is transferred from the position of grounding to the position of connecting an energy storage capacitor. Although the efficiency of raising the voltage is high, the output current of AAT1282 and ADP1560 is regulated and controlled by a linear scheme. The scheme is limited by the upper limit voltage of the EDLC and the lower limit voltage of the LED driving, the available energy storage capacity is limited, and a large-capacity high-voltage series EDLC capacitor is required to be used. It controls the output current in a linear fashion with further losses in both energy efficiency and device capacity utilization.
Aiming at the problem of low energy utilization rate of a driving circuit of a light emitting diode in the related art, an effective solution is not provided at present.
Disclosure of Invention
The present invention is directed to a driving circuit of a light emitting diode and a driving control method thereof, so as to solve the problem of low energy utilization rate of the driving circuit of the light emitting diode in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided a driving circuit of a light emitting diode, including: a battery; the inductor is connected with the battery; an electric double layer capacitor connected between a negative electrode of the battery and a first end of the inductance; the source electrode of the first field effect transistor is connected with a first node, the drain electrode of the first field effect transistor is connected with the second end of the inductor, and the first node is a node between the double electric layer capacitor and the negative electrode of the battery; the source electrode of the second field effect transistor is connected with the first node, and the drain electrode of the second field effect transistor is connected with the second end of the inductor; the source electrode of the third field effect transistor is connected with the anode of the battery, and the drain electrode of the third field effect transistor is connected with the second end of the inductor; the light emitting diode is connected between the first node and the source electrode of the first field effect transistor; and the controller is respectively connected with the grid electrode of the first field effect transistor, the grid electrode of the second field effect transistor and the grid electrode of the third field effect transistor and is used for charging the electric double-layer capacitor by controlling the switching states of the second field effect transistor and the third field effect transistor and driving the light-emitting diode to emit light by controlling the switching states of the first field effect transistor and the second field effect transistor.
Further, the driving circuit further includes: the drain electrode of the fourth field effect transistor is connected with the controller; the drain electrode of the fifth field effect transistor is connected with the source electrode of the fourth field effect transistor, the body end of the fifth field effect transistor is connected with the grid electrode of the second field effect transistor, the source electrode of the fifth field effect transistor is connected to the first node, and the grid electrode of the fifth field effect transistor is connected with the controller; the first input end of the amplifier is connected with the second end of the inductor and the controller respectively, the second input end of the amplifier is connected to a second node, the output end of the amplifier is connected to the grid electrode of the fourth field-effect tube, and the second node is a node between the drain electrode of the fifth field-effect tube and the source electrode of the fourth field-effect tube; and a first movable contact of the first switch is connected with the grid electrode of the first field effect transistor, a second movable contact of the first switch is connected with the grid electrode of the third field effect transistor, and a common end contact of the first switch is connected with the controller.
Further, the controller includes: the current deviation acquisition module is connected with the drain electrode of the fourth field effect transistor; the first voltage deviation acquisition module is connected with a first input end of the amplifier; the second voltage deviation acquisition module is connected with the positive electrode of the battery; and the control module is respectively connected with the current deviation acquisition module, the first voltage deviation acquisition module and the second voltage deviation acquisition module and is used for controlling the on-off states of the first field effect transistor, the second field effect transistor and the third field effect transistor according to acquisition signals from the current deviation acquisition module, the first voltage deviation acquisition module and the second voltage deviation acquisition module.
Further, the current collection module includes: the first input end of the first limiting amplifier is connected with the drain electrode of the fourth field effect transistor, the second input end of the first limiting amplifier is used for receiving preset current, and the first voltage acquisition module comprises: the first input end of the second limiting amplifier is connected with the second end of the inductor, the second input end of the second limiting amplifier is used for receiving a first preset voltage, and the second voltage acquisition module comprises: the first input end of the third amplifier is connected with the anode of the battery, the second input end of the third amplifier is used for receiving a second preset voltage, and the control module comprises: the input end of the fourth limiting amplifier is respectively connected with the output end of the first limiting amplifier, the output end of the second limiting amplifier and the output end of the third amplifier; the first input end of the comparator is connected with the output end of the fourth limiting amplifier, and the second input end of the comparator is used for receiving the first driving signal; and the input end of the trigger is connected with the output end of the comparator, and the output end of the trigger is respectively connected with the common end contact of the first switch and the grid electrode of the fifth field effect transistor.
Further, the driving circuit further includes: and a common end contact of the second switch is connected with the switch position control end of the first switch, a first movable contact of the second switch is used for receiving a second driving signal, and a second movable contact of the second switch is connected with the controller.
Further, the second driving signal is a square wave signal, and the time ratio of the high-level signal to the low-level signal in the square wave signal is 3: 2.
Further, the light emitting diode includes a plurality of light emitting diodes connected in series.
In order to achieve the above object, according to one aspect of the present invention, there is provided a driving control method of a light emitting diode, which can be performed by any one of the driving circuits of the light emitting diode provided in the above aspects of the present invention,
in order to achieve the above object, according to one aspect of the present invention, there is provided a driving control method of a light emitting diode, in which a light emitting diode driving circuit includes a battery, an inductor, an electric double layer capacitor, and a light emitting diode, the control method including: controlling the battery, the inductor and the electric double layer capacitor to form a first loop so that the battery charges the inductor and the electric double layer capacitor; controlling the inductance and the electric double layer capacitor to form a second loop so that the inductance charges the electric double layer capacitor; the double-layer capacitor transfers energy into an inductive magnetic field for storing energy through a second loop; and controlling the electric double layer capacitor, the inductor and the light emitting diode to form a third loop so that the electric double layer capacitor discharges to the light emitting diode.
Further, the light emitting diode driving circuit further includes a first field effect transistor, a second field effect transistor, and a third field effect transistor, wherein the inductor is connected to the battery, the electric double layer capacitor is connected between a negative electrode of the battery and a first end of the inductor, a source electrode of the first field effect transistor is connected to a first node, a drain electrode of the first field effect transistor is connected to a second end of the inductor, wherein the first node is a node between the electric double layer capacitor and the negative electrode of the battery, a source electrode of the second field effect transistor is connected to the first node, a drain electrode of the second field effect transistor is connected to a second end of the inductor, a source electrode of the third field effect transistor is connected to a positive electrode of the battery, a drain electrode of the third field effect transistor is connected to a second end of the inductor, and the light emitting diode is connected between the first node and the first field effect transistor, wherein the third field effect transistor is controlled to be turned on so that, and controlling the second field effect transistor to be conducted so that the inductor and the electric double layer capacitor form a second loop, and controlling the first field effect transistor to be conducted so that the electric double layer capacitor, the inductor and the light emitting diode form a third loop.
According to the invention, the light emitting diode driving circuit comprises the following structures: a battery; the inductor is connected with the battery; an electric double layer capacitor connected between a negative electrode of the battery and a first end of the inductance; the source electrode of the first field effect transistor is connected with a first node, the drain electrode of the first field effect transistor is connected with the second end of the inductor, and the first node is a node between the double electric layer capacitor and the negative electrode of the battery; the source electrode of the second field effect transistor is connected with the first node, and the drain electrode of the second field effect transistor is connected with the second end of the inductor; the source electrode of the third field effect transistor is connected with the anode of the battery, and the drain electrode of the third field effect transistor is connected with the second end of the inductor; the light emitting diode is connected between the first node and the first field effect transistor; and the controller is respectively connected with the grid electrode of the first field effect transistor, the grid electrode of the second field effect transistor and the grid electrode of the third field effect transistor and is used for charging the electric double-layer capacitor by controlling the switching states of the second field effect transistor and the third field effect transistor and driving the light-emitting diode to emit light by controlling the switching states of the first field effect transistor and the second field effect transistor. The double-electric-layer capacitor is charged by controlling the switching states of the second field effect tube and the third field effect tube, and the light emitting diode is driven to emit light by controlling the switching states of the first field effect tube and the second field effect tube, so that energy conversion is realized by adopting a high-energy-efficiency switching mode, the energy efficiency and device capacity utilization rate loss caused by the fact that output current is controlled in a linear mode in the prior art is avoided, the problem that the energy utilization rate of a driving circuit of the light emitting diode is low in the prior art is solved, and the effects of improving the energy efficiency and the element utilization rate and reducing the production cost of the system are achieved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1a and 1b are an external schematic view and an internal circuit configuration view of a driving circuit employing an EDLC according to the related art, respectively;
fig. 2 is a circuit diagram of a driving circuit employing an ADP1560 according to the related art;
FIG. 3 is a schematic diagram of a driving circuit according to a first embodiment of the present invention;
FIG. 4 is a schematic diagram of a driving circuit according to a second embodiment of the present invention; and
fig. 5 is a flowchart of a driving control method according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
The embodiment of the invention provides a driving circuit of a light emitting diode, which is specifically described as follows:
fig. 3 is a schematic diagram of a driving circuit according to a first embodiment of the present invention, which includes a battery B, an inductor L1, an electric double layer capacitor CS, a first field effect transistor Q1, a second field effect transistor Q2, a third field effect transistor Q3, a light emitting diode LED, and a controller 10, as shown in fig. 3.
Wherein electric double layer capacitor CS is connected between the negative electrode of battery B and the first end of inductance L1; the source of the first field-effect transistor Q1 is connected to a node (hereinafter referred to as a first node) between the electric double layer capacitor and the negative electrode of the battery B, and the drain of the first field-effect transistor Q1 is connected to the second terminal of the inductor L1; the source electrode of the second field effect transistor Q2 is also connected with the first node, and the drain electrode of the second field effect transistor Q2 is also connected with the second end of the inductor L1; the source electrode of the third field effect transistor Q3 is connected with the positive electrode of the battery B, and the drain electrode of the third field effect transistor Q3 is also connected with the second end of the inductor L1; the light emitting diode LED is connected between the first node and the source electrode of the first field effect transistor Q1; the controller 10 is connected to the gate of the first fet Q1, the gate of the second fet Q2, and the gate of the third fet Q3, respectively, and is configured to charge the electric double layer capacitor by controlling the switching states of the second fet Q2 and the third fet Q3, and to drive the light emitting diode LED to emit light by controlling the switching states of the first fet Q1 and the second fet Q2.
The energy conversion with high energy efficiency is realized by controlling the switching states of the second field effect tube and the third field effect tube, charging the double electric layer capacitor in a switching voltage reduction mode and driving the light emitting diode to emit light in a switching voltage boosting mode by controlling the switching states of the first field effect tube and the second field effect tube, energy efficiency and device capacity utilization rate loss caused by using high-voltage EDLC and controlling output current in a linear mode in the prior art are avoided, the problem that a driving circuit of the light emitting diode in the prior art is low in energy utilization rate is solved, and the effects of improving the energy efficiency and the element utilization rate and reducing the production cost of the system are further achieved.
Fig. 4 is a schematic diagram of a driving circuit according to a second embodiment of the present invention, and as shown in fig. 4, the driving circuit according to the second embodiment of the present invention is different from the driving circuit according to the first embodiment of the present invention in that the driving circuit according to the second embodiment of the present invention further includes: a fourth field effect transistor Q4, a fifth field effect transistor Q5, an amplifier a5 and a first switch K1.
Wherein, the drain electrode of the fourth field effect transistor Q4 is connected with the controller 10; the drain electrode of the fifth field effect transistor Q5 is connected with the source electrode of the fourth field effect transistor Q4, the fifth field effect transistor Q5 is an image field effect transistor which is divided from the second field effect transistor and has the same geometric distribution with a small proportion, and the fifth field effect transistor Q5 and the second field effect transistor Q2 share the same source and gate; the first input end of the amplifier a5 is connected to the second end of the inductor and the controller 10, respectively, the second input end of the amplifier a5 is connected to a second node, the output end of the amplifier a5 is connected to the gate of the fourth fet Q4, wherein the second node is a node between the drain of the fifth fet Q5 and the source of the fourth fet Q4; specifically, the second field effect transistor Q2, the fourth field effect transistor Q4, the fifth field effect transistor Q5 and the amplifier a5 constitute a sampling circuit for sampling the mirror current of the second field effect transistor Q2; the first moving contact of the first switch K1 is connected with the gate of the first fet Q1, the second moving contact of the first switch K1 is connected with the gate of the third fet Q3, and the common contact of the first switch K1 is connected with the controller 10.
Specifically, the controller 10 may include a current deviation collecting module connected to the drain of the fourth fet Q4, a first voltage deviation collecting module connected to the second input terminal of the inductor, a second voltage deviation collecting module connected to the positive terminal of the battery B, and a control module respectively connected to the current deviation collecting module, the first voltage deviation collecting module, and the second voltage deviation collecting module, wherein the control module controls the on/off states of the first fet Q1, the second fet Q2, and the third fet Q3 according to the collected signals from the current deviation collecting module, the first voltage deviation collecting module, and the second voltage deviation collecting module.
The operation principle of the driving circuit according to the second embodiment of the present invention is illustrated by taking the current deviation collecting module as a first limiting amplifier a1 (a 1 is a differential amplifier), the first voltage deviation collecting module is a second limiting amplifier a2 (a 2 is a differential amplifier), the second voltage deviation collecting module is a third amplifier A3, the control module includes a fourth limiting amplifier a4 (a 4 is a summing amplifier), a comparator C and a flip-flop D, wherein a first input terminal of the first limiting amplifier a1 is connected to a drain of a fourth field effect transistor Q4, a second input terminal of the first limiting amplifier a1 is configured to receive a preset current I1, a first input terminal of the second limiting amplifier a2 is connected to a second terminal of an inductor, a second input terminal of the second limiting amplifier a2 is configured to receive a first preset voltage V1, a first input terminal of the third limiting amplifier A3 is connected to a positive electrode of the battery B, the second input end of the third amplifier A3 is used for receiving a second preset voltage V2, the input end of the summing amplifier a4 is connected with the output ends of a1, a2 and A3, the output end of a4 is connected to one input end of a comparator C, the other input end of the comparator C receives a sawtooth wave signal with fixed amplitude, the output end of the comparator C is connected with a trigger D, and the non-inverting and inverting outputs of the trigger D are respectively connected with the grid of the fifth field-effect transistor Q5 and the common end contact of the first switch K1. The preset current I1 is a light emitting diode driving current, i.e., a discharging current, which is defined according to application requirements, the preset voltage V1 is a charging voltage, i.e., a voltage to be reached and maintained when the energy storage capacitor is used for energy storage, and the preset voltage V2 is a discharging voltage, i.e., a minimum voltage to which the battery is allowed to be lowered when energy is extracted from the battery. In the second embodiment of the present invention, the second fet Q2, the fourth fet Q4, the fifth fet Q5 and the amplifier a5 form a current mirror structure, and necessary electronic devices R1, C1, R2 and C2 are further disposed on the periphery of the current mirror structure, and the specific positional relationship is shown in fig. 4, and the operation principle of the driving circuit according to the second embodiment of the present invention is specifically as follows:
step 1: the proportion of time that Q2 and Q3 are alternately turned on is controlled so that battery B charges capacitor CS. Specifically, when the driving circuit starts to work, the Q2 and the Q3 are alternately conducted, the frequency of the alternate conduction of the Q2 and the Q3 is the frequency of the sawtooth waves, and the time proportion of the alternate conduction is controlled by the outputs of A2 and A3. In this step, the current flowing in the Q2 current mirror structure is in the opposite direction to the normal operating current of the current mirror, and a1 is in reverse saturation and outputs a low voltage of a certain magnitude. The first input terminal of the a2 amplifier is connected to the node between R2 and C2 to realize the voltage collection across the electric double layer capacitor CS, the a2 amplifier amplifies the difference between the actual capacitance voltages of the predetermined voltage V1 and CS, and when the voltage of the capacitance CS is much lower than the predetermined voltage V1, the output of the a2 is limited to a low voltage of a certain magnitude or a value proportional to the deviation. A3 amplifies the difference between the current voltage of battery B and the allowable minimum voltage V2, and A3 outputs a low voltage of a certain magnitude as long as the current battery voltage is higher than the allowable minimum voltage. Only when the battery voltage is close to the lowest voltage allowed, a3 is output as a voltage value associated with the deviation. A4 is a summing amplifier designed to output slightly higher than the lowest amplitude of a fixed amplitude sawtooth when all of A1, A2 and A3 output the lowest voltage; the duty cycle output by the comparator C at this time is the maximum duty cycle. When the voltage of the capacitor CS approaches the preset voltage V1 or/and the voltage of the battery B approaches the lowest allowable voltage V2, the output of A4 rises, the duty ratio of the output of C is reduced compared with the sawtooth wave until the output of A4 exceeds the amplitude of the sawtooth wave, and the duty ratio of the output of C is reduced to zero. Specifically, the alternate conduction of Q2 and Q3 is driven by the complementary output of flip-flop D, D is a dead time generator, which has a frequency corresponding to the sawtooth wave when comparator C receives a pulse train with a duty cycle related to the magnitude of the error generated by the comparison of the amount of error effectively controlled at its first input with the sawtooth wave received at its second input, and which is fed to dead time generator D to generate the complementary output by D after insertion of a dead time, i.e., the variable duty cycle train of C passes through the dead time controlled flip-flop D to generate the drive signals for the switching of Q2 and Q3, with a higher duty cycle corresponding to a longer conduction of Q3, making the voltage of CS larger, and vice versa making it smaller. The dead time is a time when neither Q2 nor Q3 is turned on. Ideally, Q2 and Q3 are turned on alternately, i.e., Q2 and Q3 are driven by C and its inverted phase. However, the switch can not be instantly switched, so that the D dead time generator can complete the function by switching off the former field effect transistor for a short time and then switching on the latter field effect transistor. If no dead time is inserted, Q2 and Q3 are on simultaneously for a short period of time, which will result in a short circuit to the battery. The feedback process described above allows the system to proceed to step 2 as long as the battery is still able to maintain energy output, eventually causing the battery to reach a predetermined voltage.
Step 2: and maintaining the voltage of the capacitor CS, and waiting for an external trigger signal, wherein the external trigger signal is used for indicating the capacitor CS to discharge to the light-emitting diode LED. Specifically, during the whole step 2, only a2 actually controls the duty ratio when the voltage of the battery B is not lower than the preset voltage V2, and the voltage of the capacitor CS is maintained to be stable at the preset voltage V1.
And step 3: after receiving an external trigger signal, the Q1 and the Q2 are controlled to be alternately conducted, the stored energy of the capacitor CS is discharged through the light-emitting diode LED with constant current, and the light-emitting diode LED flashes. Specifically, during step 3, a3 outputs the lowest voltage of a certain magnitude, since no more energy is taken from battery B; the voltage of the capacitor CS begins to drop, and a2 will output the lowest voltage quickly; a1 is also the output lowest voltage at the beginning; at this time, the output of a4 is also the lowest voltage, and the maximum duty cycle is output corresponding to C. In the time of conducting Q2, the energy storage capacitor CS discharges through the inductor L1, and the current of the inductor L1 gradually increases; during the conduction of Q1, the current of inductor L1 is conducted to the LED via Q1. The conduction voltage of the LED is between 3.2V and 3.5V and is greater than the voltage of the energy storage capacitor; the current through the inductor is reduced during this period. In this state, a larger duty cycle results in a larger LED drive current.
In the driving circuit of the second embodiment of the present invention, the differential amplifier a1 is designed to detect the current discharged to the LED, and when the LED current approaches the predetermined current, a voltage related to the deviation is outputted, which is amplified by a4 and then the duty ratio of C is adjusted to stabilize the LED current at the predetermined value. The detection of the LED discharge current is realized by a current mirror structure of Q2, and the pulse current during the charging of the inductor L is collected, and the current is proportional to the output current in the continuous mode, and the LED driving circuit with large current output also works in the continuous mode. The sampled current is smoothed to obtain a voltage value, and the voltage value is sent to an amplifier A1 to be amplified so as to control Q1 and Q2 to output a stable current in a switching mode. This current mirror is a pulse controlled intermittent current sampling channel that passes a proportional current to an input of a1 only during the time that Q2 is on; this proportional current, averaged via the RC circuit, forms a proportional value related to the average value of the intermittent current, which is proportional to the LED current when the current in the inductor is in the continuous conduction mode. The sampling circuit realizes indirect sampling of the LED current, and the detection and control of the current, namely the detection and control of the LED current.
Further, the driving circuit according to the second embodiment of the present invention further includes a second switch K2, a common terminal contact of the second switch K2 is connected to a switch position control input of the first switch K1, and a first movable contact of the second switch K2 is configured to receive a second driving signal, where the second driving signal is a square wave signal having a time ratio of a high level signal to a low level signal of 3:2, a frequency of the square wave signal is 100Hz, and a second movable contact of the second switch K2 is connected to one control bit output terminal of the controller, and the control words and bits in the controller include an output current setting register word, a charging voltage selection bit, a flash/charging control bit m1, a stabilization/alternation control bit m2, and a discharging voltage selection bit; the output current setting register word is a number representing the required output current, the number is converted into voltage and output to the first voltage deviation acquisition module, and the charging voltage selection bit is used for selecting two different charging voltages; the flash/charge control bit m1 is that when the second switch K2 connects the common terminal contact of K2 to m1 according to the control of the m2 bit, whether the connection of K1 is flash or charge is controlled by the content of m 1; the steady/alternate control bit m2 is used to control whether the common contact of K2 is connected to the second drive signal or the m1 bit.
When the common terminal contact of the second switch K2 is connected with the contact receiving the flashing/charging control bit m1, the driving circuit stores and maintains energy according to the step 1-2 or drives the light emitting diode LED according to the step 3 according to the state of m 1; when the common terminal contact of the second switch K2 is connected with the contact for receiving the square wave signal, the driving circuit alternately charges, maintains and drives the light-emitting diode according to the control of the square wave, so that the light-emitting diode LED continuously emits light in a pulse mode and is used as a flashlight; the LED only allows a small continuous current when the flashlight is made, so that the LED is prevented from being burnt out by overheating. This current, i.e., the discharge current, is still specified from the outside, and is usually only 1/5 or less of the flash current. The normal working voltage range of the lithium battery B is 3.55V-4.2V, the highest voltage of the energy storage capacitor is 2.6V-2.7V, the light emitting voltage of the LED is 3.2V-3.5V, and the 2:3 square wave can ensure that the output current can be maintained at a preset value in the charging and discharging process. If the voltage of the battery B cannot be kept higher than the lowest allowable voltage, the LED current will be caused to drop accordingly until the current can not be output at all. In this embodiment, the lowest allowable battery voltage may also be selected to be lower than the voltage that the battery can effectively output, in which case the flashlight output will be maintained until the battery itself fails.
The driving circuit of the second embodiment of the invention forms a step-down switch modulator through Q2 and Q3, and stores energy on the EDLC mass capacitor CS in a switching mode during energy storage; when the LED is driven to discharge, a boosting circuit is formed by Q1 and Q2, and energy is obtained from CS to generate driving voltage output. The minimum CS voltage at which stable output can be maintained during driving is mainly determined by the on-resistance of Q2, and the range of utilization of the energy storage capacity is determined by the maximum allowable voltage of the EDLC and the minimum voltage. The capacitance C (F) required per steady output I (A) is 0.32. multidot.I, calculated with 80% boost efficiency, 1.4V to 2.7V available voltage range and 200ms regulated current to drive a single 3.4V forward drop LED. These parameters are significantly better than other schemes.
Further, the light emitting diode in the driving circuit of the light emitting diode provided by any of the above embodiments of the present invention may be formed by connecting a plurality of diodes in series, so as to drive the light emitting diodes connected in series to emit light.
The embodiment of the present invention further provides a driving control method for a light emitting diode, where the driving control method can be executed by any one of the driving circuits provided in the above embodiments of the present invention, and the driving control method provided in the embodiment of the present invention is specifically described below with reference to the driving circuit provided in the above content of the embodiment of the present invention:
fig. 5 is a flowchart of a drive control method according to an embodiment of the present invention, which includes the following steps S502 to S506, as shown in fig. 5:
s502: controlling the battery, the inductor and the electric double layer capacitor to form a first loop so that the battery charges the inductor and the electric double layer capacitor; specifically, the field effect transistor Q3 in the driving circuit can be controlled to be turned on to realize that the battery, the inductor and the electric double layer capacitor form a first loop.
S504: controlling the inductance and the electric double layer capacitor to form a second loop so that the inductance charges the electric double layer capacitor; specifically, the field effect transistor Q2 in the driving circuit may be controlled to be turned on to realize the inductor and the electric double layer capacitor to form a second circuit, the inductor is used for charging the electric double layer capacitor by transferring the inductor energy storage to the capacitor during the freewheeling period, and then the voltage of the electric double layer capacitor is maintained by controlling the time ratio of the operation of the first and second circuits.
S506: and the double-layer capacitor is enabled to transfer energy into inductive magnetic field energy storage through the second loop, and specifically, the capacitive energy storage is enabled to discharge through the inductor and transfer energy into inductive magnetic field energy storage.
S508: controlling the electric double layer capacitor, the inductor and the light emitting diode to form a third loop so that the electric double layer capacitor and the inductor are connected in series to discharge electricity to the light emitting diode together; specifically, the field effect transistor Q1 in the driving circuit can be controlled to be turned on to realize that the electric double layer capacitor, the inductor and the light emitting diode form a third loop, and then stable current driving to the light emitting diode is maintained by controlling the time proportion of the operation of the third loop and the second loop.
The driving control method of the embodiment of the invention realizes the charging of the double-electric-layer capacitor or the light emitting of the light emitting diode by controlling the on-off state of each loop, realizes the energy conversion by adopting a high-energy-efficiency switching mode, avoids the loss of energy efficiency and device capacity utilization rate caused by the linear mode control of output current in the prior art, solves the problem of low energy utilization rate of a driving circuit of the light emitting diode in the prior art, and further achieves the effects of improving the energy efficiency and the element utilization rate and reducing the system production cost.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A driving circuit for a light emitting diode, comprising:
a battery;
an inductor connected to the battery;
an electric double layer capacitor connected between a negative electrode of the battery and a first end of the inductance;
a first field effect transistor, wherein a source of the first field effect transistor is connected to a first node, and a drain of the first field effect transistor is connected to a second end of the inductor, wherein the first node is a node between the electric double layer capacitor and a negative electrode of the battery;
a source electrode of the second field effect transistor is connected with the first node, and a drain electrode of the second field effect transistor is connected with a second end of the inductor;
a source electrode of the third field effect transistor is connected with the anode of the battery, and a drain electrode of the third field effect transistor is connected with the second end of the inductor;
the light emitting diode is connected between the first node and the source electrode of the first field effect transistor; and
and the controller is connected with the grid electrode of the first field effect transistor, the grid electrode of the second field effect transistor and the grid electrode of the third field effect transistor respectively and used for charging the electric double layer capacitor by controlling the switching states of the second field effect transistor and the third field effect transistor and driving the light-emitting diode to emit light by controlling the switching states of the first field effect transistor and the second field effect transistor.
2. The driving circuit according to claim 1, further comprising:
the drain electrode of the fourth field effect transistor is connected with the controller;
the fifth field effect transistor and the second field effect transistor are current mirror field effect transistors with source electrodes and grid electrodes connected together, and the drain electrode of the fifth field effect transistor is connected with the source electrode of the fourth field effect transistor;
a first input end of the amplifier is connected with the second end of the inductor and the controller respectively, a second input end of the amplifier is connected to a second node, an output end of the amplifier is connected to a grid electrode of the fourth field effect transistor, and the second node is a node between a drain electrode of the fifth field effect transistor and a source electrode of the fourth field effect transistor; and
the first movable contact of the first switch is connected with the grid electrode of the first field effect transistor, the second movable contact of the first switch is connected with the grid electrode of the third field effect transistor, and the common end contact of the first switch is connected with the controller.
3. The drive circuit according to claim 2, wherein the controller comprises:
the current deviation acquisition module is connected with the drain electrode of the fourth field effect transistor;
the first voltage deviation acquisition module is connected with the first input end of the amplifier;
the second voltage deviation acquisition module is connected with the positive electrode of the battery; and
and the control module is respectively connected with the current deviation acquisition module, the first voltage deviation acquisition module and the second voltage deviation acquisition module and is used for controlling the on-off states of the first field effect transistor, the second field effect transistor and the third field effect transistor according to acquisition signals from the current deviation acquisition module, the first voltage deviation acquisition module and the second voltage deviation acquisition module.
4. The drive circuit according to claim 3,
the current collection module includes:
a first input end of the first limiting amplifier is connected with the drain electrode of the fourth field effect transistor, a second input end of the first limiting amplifier is used for receiving preset current,
the first voltage acquisition module includes:
a second limiting amplifier, a first input terminal of the second limiting amplifier is connected with a second terminal of the inductor, a second input terminal of the second limiting amplifier is used for receiving a first preset voltage,
the second voltage acquisition module comprises:
a third amplifier, a first input terminal of the third amplifier is connected with the anode of the battery, a second input terminal of the third amplifier is used for receiving a second preset voltage,
the control module includes:
the input end of the fourth limiting amplifier is respectively connected with the output end of the first limiting amplifier, the output end of the second limiting amplifier and the output end of the third amplifier;
a first input end of the comparator is connected with an output end of the fourth limiting amplifier, and a second input end of the comparator is used for receiving a first driving signal; and
and the input end of the trigger is connected with the output end of the comparator, and the output end of the trigger is respectively connected with the common end contact of the first switch and the grid electrode of the fifth field effect transistor.
5. The driving circuit according to claim 2, further comprising:
and a common terminal contact of the second switch is connected with the switch position control terminal of the first switch, a first movable contact of the second switch is used for receiving a second driving signal, and a second movable contact of the second switch is connected with a flash/charge control position m1 from the controller.
6. The driving circuit according to claim 5, wherein the second driving signal is a square wave signal, and a time ratio of a high level signal to a low level signal in the square wave signal is 3: 2.
7. The driving circuit of claim 1, wherein the light emitting diode comprises a plurality of series-connected light emitting diodes.
8. A driving control method of a light emitting diode, wherein a light emitting diode driving circuit includes a battery, an inductor, an electric double layer capacitor, and a light emitting diode, the control method comprising:
controlling the battery, the inductor, and the electric double layer capacitor to form a first loop so that the battery charges the inductor and the electric double layer capacitor;
controlling the inductance and the electric double layer capacitor to form a second loop so that the inductance charges the electric double layer capacitor;
causing, by the second loop, the electric double layer capacitor to transfer energy to the magnetic field storage energy of the inductance; and
controlling the electric double layer capacitor, the inductor, and the light emitting diode to form a third circuit to discharge the electric double layer capacitor to the light emitting diode.
9. The drive control method according to claim 8, wherein the light emitting diode drive circuit further comprises a first field effect transistor, a second field effect transistor, and a third field effect transistor, wherein,
the inductor is connected to the battery and is connected to the battery,
the electric double layer capacitor is connected between a negative electrode of the battery and a first end of the inductance,
a source of the first field effect transistor is connected to a first node, and a drain of the first field effect transistor is connected to a second terminal of the inductor, wherein the first node is a node between the electric double layer capacitor and a negative electrode of the battery,
the source electrode of the second field effect transistor is connected with the first node, the drain electrode of the second field effect transistor is connected with the second end of the inductor,
the source electrode of the third field effect transistor is connected with the anode of the battery, the drain electrode of the third field effect transistor is connected with the second end of the inductor,
the light emitting diode is connected between the first node and the source of the first field effect transistor,
wherein,
controlling the third field effect transistor to be turned on so that the battery, the inductor, and the electric double layer capacitor constitute the first circuit,
controlling the second field effect transistor to be turned on so that the inductor and the electric double layer capacitor constitute the second circuit,
and controlling the first field effect transistor to be turned on so that the electric double layer capacitor, the inductor and the light emitting diode constitute the third circuit.
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| CN102238766A (en) * | 2010-04-20 | 2011-11-09 | 成都蜀昌科技有限公司 | General high-efficiency long-life driving circuit for wide voltage non-inductance semiconductor illumination |
| JP2011233442A (en) * | 2010-04-28 | 2011-11-17 | Toshiba Information Systems (Japan) Corp | Led drive device |
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